SUMMARY:Nestin is one of the intermediate filaments abundantly produced in the developing central nervous system and somites in the embryonic stage. Nestin is also reportedly detected in gliomas/glioblastomas. We retested nestin expression in brain tumors having a range of malignancy grades using immunostaining. The intensity of nestin immunostaining roughly paralleled the malignancy grade of the gliomas. However, many tumors were negative for nestin immunostaining, while nestin immunostaining was invariably detected in tumor endothelium regardless of glioma malignancy grades or brain tumor types. We suspected that angiogenic epithelial cells may express nestin, and we found that nestin was highly positive in bovine aortic endothelial cells in static culture. However, nestin expression decreased when the endothelial cells underwent laminar shear stress flow, under which endothelial cells exhibit differentiated features and a decreased rate of growth. Because nestin is highly expressed in growing endothelial cells, we examined its expression in hemangioblastomas because hemangioblasts are thought to be a precursor for angiogenic epithelial cells. As expected, nestin immunostained strongly in all four samples of hemangioblastomas. We suggest that nestin is not only a marker for neuroepithelial stem cells and glioma cells but also for tumor endothelial cells during rapid growth. (Lab Invest 2002, 82:345-351).

We have successfully prepared cell-sized giant liposomes encapsulating desired amounts of actoHMM, a mixture of actin filament (F-actin) and heavy meromyosin (HMM, an actin-related molecular motor), in the presence of 5 mM MgCl 2 and 50 mM KCl. We employed a spontaneous transfer method to prepare those liposomes. In the absence of HMM, F-actin was distributed homogeneously inside the liposomes. In contrast, when F-actin was encapsulated in liposomes together with HMM, network structures were generated. Such network structures are attributable to the cross-linking of F-actin by HMM.

Abstract-Furin, a yeast Kex2-family endoprotease, converts many vasoregulatory propeptides, including protransforming growth factor (TGF)-␤ to their mature forms. We examined whether furin expression is regulated by shear stress in vivo and in vitro. When an arteriovenous shunt was placed between the carotid artery and external jugular vein in rabbits, furin and TGF-␤ were highly expressed in shear stress-loaded endothelial cells. Exposure of bovine aortic endothelial cells in culture to shear stress induced furin and TGF-␤ expression in a similar manner. Molecular analysis of furin expression in bovine aortic endothelial cells revealed that shear stress increases the furin gene expression at transcriptional levels. Furthermore, TGF-␤ itself increased the furin mRNA levels. Shear-mediated furin expression was partly mediated by TGF-␤ because shear-induced furin mRNA levels were considerably decreased by overexpression of the truncated form of the TGF-␤ type II receptor. Likewise, blockade of furin activity by a furin inhibitor significantly decreased the endothelial production of mature TGF-␤. Taken